"Mary Anne should never have thrown away that chain letter she got in the mail. Ever since she did, bad things have been happening to everybody in the Baby-sitters Club. With Halloween coming up, Mary Anne's even more worried--what kind of spooky thing will happen next? Then Mary Anne finds a new note in her mailbox: Wear this bad-luck charm, it says. Or else. Mary Anne's got to do what the note says. But who sent the charm? And why did this person...